Verwenden Sie ein Objektpersistenzmodell auf hoher Ebene für DynamoDB mit einem AWS SDK

Das folgende Codebeispiel zeigt, wie Create, Read, Update und Delete (CRUD) sowie Batch-Operationen mit einem Objektpersistenzmodell für DynamoDB und einem ausgeführt werden. AWS SDK

Weitere Informationen finden Sie unter Object-Persistence-Modell.

.NET

AWS SDK for .NET

Anmerkung

Es gibt noch mehr dazu GitHub. Sie sehen das vollständige Beispiel und erfahren, wie Sie das AWS -Code-Beispiel-Repository einrichten und ausführen.

Führen Sie CRUD Operationen mit einem Objektpersistenzmodell auf hoher Ebene durch.

    /// <summary>
    /// Shows how to perform high-level CRUD operations on an Amazon DynamoDB
    /// table.
    /// </summary>
    public class HighLevelItemCrud
    {
        public static async Task Main()
        {
            var client = new AmazonDynamoDBClient();
            DynamoDBContext context = new DynamoDBContext(client);
            await PerformCRUDOperations(context);
        }

        public static async Task PerformCRUDOperations(IDynamoDBContext context)
        {
            int bookId = 1001; // Some unique value.
            Book myBook = new Book
            {
                Id = bookId,
                Title = "object persistence-AWS SDK for.NET SDK-Book 1001",
                Isbn = "111-1111111001",
                BookAuthors = new List<string> { "Author 1", "Author 2" },
            };

            // Save the book to the ProductCatalog table.
            await context.SaveAsync(myBook);

            // Retrieve the book from the ProductCatalog table.
            Book bookRetrieved = await context.LoadAsync<Book>(bookId);

            // Update some properties.
            bookRetrieved.Isbn = "222-2222221001";

            // Update existing authors list with the following values.
            bookRetrieved.BookAuthors = new List<string> { " Author 1", "Author x" };
            await context.SaveAsync(bookRetrieved);

            // Retrieve the updated book. This time, add the optional
            // ConsistentRead parameter using DynamoDBContextConfig object.
            await context.LoadAsync<Book>(bookId, new DynamoDBContextConfig
            {
                ConsistentRead = true,
            });

            // Delete the book.
            await context.DeleteAsync<Book>(bookId);

            // Try to retrieve deleted book. It should return null.
            Book deletedBook = await context.LoadAsync<Book>(bookId, new DynamoDBContextConfig
            {
                ConsistentRead = true,
            });

            if (deletedBook == null)
            {
                Console.WriteLine("Book is deleted");
            }
        }
    }

Führen Sie Batch–Schreiboperationen unter Verwendung eines übergeordneten Object-Persistence-Modells durch.

    /// <summary>
    /// Performs high-level batch write operations to an Amazon DynamoDB table.
    /// This example was written using the AWS SDK for .NET version 3.7 and .NET
    /// Core 5.0.
    /// </summary>
    public class HighLevelBatchWriteItem
    {
        public static async Task SingleTableBatchWrite(IDynamoDBContext context)
        {
            Book book1 = new Book
            {
                Id = 902,
                InPublication = true,
                Isbn = "902-11-11-1111",
                PageCount = "100",
                Price = 10,
                ProductCategory = "Book",
                Title = "My book3 in batch write",
            };

            Book book2 = new Book
            {
                Id = 903,
                InPublication = true,
                Isbn = "903-11-11-1111",
                PageCount = "200",
                Price = 10,
                ProductCategory = "Book",
                Title = "My book4 in batch write",
            };

            var bookBatch = context.CreateBatchWrite<Book>();
            bookBatch.AddPutItems(new List<Book> { book1, book2 });

            Console.WriteLine("Adding two books to ProductCatalog table.");
            await bookBatch.ExecuteAsync();
        }

        public static async Task MultiTableBatchWrite(IDynamoDBContext context)
        {
            // New Forum item.
            Forum newForum = new Forum
            {
                Name = "Test BatchWrite Forum",
                Threads = 0,
            };
            var forumBatch = context.CreateBatchWrite<Forum>();
            forumBatch.AddPutItem(newForum);

            // New Thread item.
            Thread newThread = new Thread
            {
                ForumName = "S3 forum",
                Subject = "My sample question",
                KeywordTags = new List<string> { "S3", "Bucket" },
                Message = "Message text",
            };

            DynamoDBOperationConfig config = new DynamoDBOperationConfig();
            config.SkipVersionCheck = true;
            var threadBatch = context.CreateBatchWrite<Thread>(config);
            threadBatch.AddPutItem(newThread);
            threadBatch.AddDeleteKey("some partition key value", "some sort key value");

            var superBatch = new MultiTableBatchWrite(forumBatch, threadBatch);

            Console.WriteLine("Performing batch write in MultiTableBatchWrite().");
            await superBatch.ExecuteAsync();
        }

        public static async Task Main()
        {
            AmazonDynamoDBClient client = new AmazonDynamoDBClient();
            DynamoDBContext context = new DynamoDBContext(client);

            await SingleTableBatchWrite(context);
            await MultiTableBatchWrite(context);
        }
    }

Weisen Sie einer Tabelle unter Verwendung eines übergeordneten Object-Persistence-Modells beliebige Daten zu.

    /// <summary>
    /// Shows how to map arbitrary data to an Amazon DynamoDB table.
    /// </summary>
    public class HighLevelMappingArbitraryData
    {
        /// <summary>
        /// Creates a book, adds it to the DynamoDB ProductCatalog table, retrieves
        /// the new book from the table, updates the dimensions and writes the
        /// changed item back to the table.
        /// </summary>
        /// <param name="context">The DynamoDB context object used to write and
        /// read data from the table.</param>
        public static async Task AddRetrieveUpdateBook(IDynamoDBContext context)
        {
            // Create a book.
            DimensionType myBookDimensions = new DimensionType()
            {
                Length = 8M,
                Height = 11M,
                Thickness = 0.5M,
            };

            Book myBook = new Book
            {
                Id = 501,
                Title = "AWS SDK for .NET Object Persistence Model Handling Arbitrary Data",
                Isbn = "999-9999999999",
                BookAuthors = new List<string> { "Author 1", "Author 2" },
                Dimensions = myBookDimensions,
            };

            // Add the book to the DynamoDB table ProductCatalog.
            await context.SaveAsync(myBook);

            // Retrieve the book.
            Book bookRetrieved = await context.LoadAsync<Book>(501);

            // Update the book dimensions property.
            bookRetrieved.Dimensions.Height += 1;
            bookRetrieved.Dimensions.Length += 1;
            bookRetrieved.Dimensions.Thickness += 0.2M;

            // Write the changed item to the table.
            await context.SaveAsync(bookRetrieved);
        }

        public static async Task Main()
        {
            var client = new AmazonDynamoDBClient();
            DynamoDBContext context = new DynamoDBContext(client);
            await AddRetrieveUpdateBook(context);
        }
    }

Verwenden Sie ein übergeordnetes Object-Persistence-Modell, um eine Tabelle abzufragen und zu scannen.

    /// <summary>
    /// Shows how to perform high-level query and scan operations to Amazon
    /// DynamoDB tables.
    /// </summary>
    public class HighLevelQueryAndScan
    {
        public static async Task Main()
        {
            var client = new AmazonDynamoDBClient();

            DynamoDBContext context = new DynamoDBContext(client);

            // Get an item.
            await GetBook(context, 101);

            // Sample forum and thread to test queries.
            string forumName = "Amazon DynamoDB";
            string threadSubject = "DynamoDB Thread 1";

            // Sample queries.
            await FindRepliesInLast15Days(context, forumName, threadSubject);
            await FindRepliesPostedWithinTimePeriod(context, forumName, threadSubject);

            // Scan table.
            await FindProductsPricedLessThanZero(context);
        }

        public static async Task GetBook(IDynamoDBContext context, int productId)
        {
            Book bookItem = await context.LoadAsync<Book>(productId);

            Console.WriteLine("\nGetBook: Printing result.....");
            Console.WriteLine($"Title: {bookItem.Title} \n ISBN:{bookItem.Isbn} \n No. of pages: {bookItem.PageCount}");
        }

        /// <summary>
        /// Queries a DynamoDB table to find replies posted within the last 15 days.
        /// </summary>
        /// <param name="context">The DynamoDB context used to perform the query.</param>
        /// <param name="forumName">The name of the forum that we're interested in.</param>
        /// <param name="threadSubject">The thread object containing the query parameters.</param>
        public static async Task FindRepliesInLast15Days(
          IDynamoDBContext context,
          string forumName,
          string threadSubject)
        {
            string replyId = $"{forumName} #{threadSubject}";
            DateTime twoWeeksAgoDate = DateTime.UtcNow - TimeSpan.FromDays(15);

            List<object> times = new List<object>();
            times.Add(twoWeeksAgoDate);

            List<ScanCondition> scs = new List<ScanCondition>();
            var sc = new ScanCondition("PostedBy", ScanOperator.GreaterThan, times.ToArray());
            scs.Add(sc);

            var cfg = new DynamoDBOperationConfig
            {
                QueryFilter = scs,
            };

            AsyncSearch<Reply> response = context.QueryAsync<Reply>(replyId, cfg);
            IEnumerable<Reply> latestReplies = await response.GetRemainingAsync();

            Console.WriteLine("\nReplies in last 15 days:");

            foreach (Reply r in latestReplies)
            {
                Console.WriteLine($"{r.Id}\t{r.PostedBy}\t{r.Message}\t{r.ReplyDateTime}");
            }
        }

        /// <summary>
        /// Queries for replies posted within a specific time period.
        /// </summary>
        /// <param name="context">The DynamoDB context used to perform the query.</param>
        /// <param name="forumName">The name of the forum that we're interested in.</param>
        /// <param name="threadSubject">Information about the subject that we're
        /// interested in.</param>
        public static async Task FindRepliesPostedWithinTimePeriod(
          IDynamoDBContext context,
          string forumName,
          string threadSubject)
        {
            string forumId = forumName + "#" + threadSubject;
            Console.WriteLine("\nReplies posted within time period:");

            DateTime startDate = DateTime.UtcNow - TimeSpan.FromDays(30);
            DateTime endDate = DateTime.UtcNow - TimeSpan.FromDays(1);

            List<object> times = new List<object>();
            times.Add(startDate);
            times.Add(endDate);

            List<ScanCondition> scs = new List<ScanCondition>();
            var sc = new ScanCondition("LastPostedBy", ScanOperator.Between, times.ToArray());
            scs.Add(sc);

            var cfg = new DynamoDBOperationConfig
            {
                QueryFilter = scs,
            };

            AsyncSearch<Reply> response = context.QueryAsync<Reply>(forumId, cfg);
            IEnumerable<Reply> repliesInAPeriod = await response.GetRemainingAsync();

            foreach (Reply r in repliesInAPeriod)
            {
                Console.WriteLine("{r.Id}\t{r.PostedBy}\t{r.Message}\t{r.ReplyDateTime}");
            }
        }

        /// <summary>
        /// Queries the DynamoDB ProductCatalog table for products costing less
        /// than zero.
        /// </summary>
        /// <param name="context">The DynamoDB context object used to perform the
        /// query.</param>
        public static async Task FindProductsPricedLessThanZero(IDynamoDBContext context)
        {
            int price = 0;

            List<ScanCondition> scs = new List<ScanCondition>();
            var sc1 = new ScanCondition("Price", ScanOperator.LessThan, price);
            var sc2 = new ScanCondition("ProductCategory", ScanOperator.Equal, "Book");
            scs.Add(sc1);
            scs.Add(sc2);

            AsyncSearch<Book> response = context.ScanAsync<Book>(scs);

            IEnumerable<Book> itemsWithWrongPrice = await response.GetRemainingAsync();

            Console.WriteLine("\nFindProductsPricedLessThanZero: Printing result.....");

            foreach (Book r in itemsWithWrongPrice)
            {
                Console.WriteLine($"{r.Id}\t{r.Title}\t{r.Price}\t{r.Isbn}");
            }
        }
    }

Eine vollständige Liste der AWS SDK Entwicklerhandbücher und Codebeispiele finden Sie unterVerwenden von DynamoDB mit einem AWS SDK. Dieses Thema enthält auch Informationen zu den ersten Schritten und Details zu früheren SDK Versionen.